Head-on collision kills four people on Barton Highway near ...

Four people are dead after two vehicles collided head on on the Barton Highway north of Canberra this morning.

The crash happened about 6:45am in heavy rain near Casuarina Lane, between the ACT village of Hall and the New South Wales town of Murrumbateman.

The female driver and male passenger of a Mitsubishi Triton ute died at the scene, as did the male driver and a male passenger of a Ford Ranger ute.

Another male passenger in the Ford was treated at the scene and taken to hospital.

Emergency crews from the ACT and NSW, including three rescue helicopters, arrived shortly after the collision.

A NSW Police spokeswoman said officers had established a crime scene and were investigating the circumstances that led to the crash.

She asked anyone with dashcam footage or other information to contact Crime Stoppers on 1800 333 000.

Southbound traffic on the Barton Highway has been diverted via Murrumbateman Road and Sutton Road to the Federal Highway.

Northbound traffic is being diverted back to Canberra. Motorists are advised to use the Federal Highway instead.

The Barton Highway will remain closed for some time.

Locals have long complained about the rural road's quality.

The highway has a 100kph speed limit and is one of only three major roads connecting Canberra with NSW.

However, it has just two lanes for most of its 52-kilometre length.

Four years ago, a NSW government report noted that the Barton Highway's casualty crash rate was about 50 per cent higher than similarly classified roads.

The federal and NSW governments have committed to widening the road into a four-lane highway.

However, this project has only just begun and is expected to take many years.